Linear motors predate the Disney project by decades. I used them in semiconductor equipment in the 70’s.
Mad_as_he$$ is correct. The Navy started the work on the electric catapult way back before 1982 and it was kicked around for quite a bit longer before then. Near as I can tell the first roller coaster using this technology was in 1996 (http://coasterpedia.net/wiki/Launched_roller_coaster)
A point that I don’t think was mentioned in the steam vs electric catapult discussion is that a steam catapult MUST be kept warm at all times. This requires a constant expenditure of energy to keep it at operating temperature (not to mention the energy required to keep steam pressure available).
An electric catapult is more like a light bulb. When not turned on it uses no energy.
This is why the sortie rate can be increased. There is essentially no recharge time between shots (depending on your electric power available of course and Ford has the power) and the net energy usage is less per shot.